Fluid resistant silicone encapsulant

ABSTRACT

A cross-linkable and cross-linked organosilicon polymer which is prepared from a mixture of a reactive polysiloxane resin having both reactive carbon-carbon double bonds and silicone-hydrogen groups, characterized by alternating structures of polycyclic polyene residue and cyclic (or tetrahedral) polysiloxane residue, and either vinyl terminated fluorine-containing polysiloxane or vinyl terminated phenyl-substituted siloxane. In an alternative embodiment, the polymer comprises a mixture of vinyl terminated phenyl-substituted polysiloxane and vinyl functional fluorosilicone elastomer with the cross-linkable and cross linked organosilicon polymer. In an alternative embodiment, the polymer comprises vinyl functional polydimethyl siloxane, and preferably high molecular weight methyl divinyl siloxane, with or without phenyl substituted siloxane.

This Application is a continuation-in part, U.S. application Ser. No.09/993,589, filed Nov. 6, 2001 now U.S. Pat. No. 6,841,647.

FIELD OF THE INVENTION

The present invention relates to a fluid resistant silicone encapsulantin the form of a cross-linked and cross-linkable organosilicon polymer.

BACKGROUND OF THE INVENTION

It is known in the art to prepare cross-linked and cross-linkablesilicone elastomers which are mainly comprised of two types of liquidpolysiloxanes; one having vinyl (or general C═C) attached to the mainchain and the other having hydrogen directly attached to silicone atoms.The addition curing (or crosslinking) reaction to form elastomericmaterials occurs through hydrosilation in the presence of platinum orother metal-containing catalysts under room temperature or heatingconditions. The substitution groups attached to the silicone chain canbe methyl, phenyl, or fluoroalkyl (mostly trifluoropropyl). Thefluoroalkyl substituted silicone (fluorosilicone) generally displaysgood chemical resistance and is commonly used as coating, potting orencapsulation material to protect electric/electronic components andassemblies.

The preparation of curable organosilicon prepolymers or cross-linkedthermosetting polymers through a hydrosilation reaction of polycyclicpolyene (providing an active C═C) and reactive cyclic polysiloxane ortetrahedral siloxysilane (providing SiH) in the presence ofplatinum-containing catalysts under heating is also known in the art.The resulting fully cross-linked materials display high rigidity andbrittleness, a relatively high T_(g), very high temperature resistance,water insensitivity and oxidation resistance. Examples of these types ofpolymers are found in U.S. Pat. No. 4,902,731 and 4,877,820.

Attempts have been made to reduce the brittleness and rigidity andincrease the toughness of such polymers. U.S. Pat. No. 5,171,817discloses such an organosilicone polymer in which reactive siloxaneelastomers having carbon-carbon double bonds are added to thecomposition to form discontinuous phases in the rigid continuous polymermatrix after curing. For example, unsaturated diphenyl dimethyl siloxaneelastomers are utilized to increase toughness and adhesion withoutreducing any of the other properties of the polymer. U.S. Pat. No.5,196,498 discloses the use of a second silicone as a modifier to reducethe viscosity and brittleness of the crosslinked polymers. The secondsilicone compound, which has reactive hydrocarbyl group, is a cyclicsiloxane and most preferably tetravin yltetramethyl cyclotetrasiloxaneor pentavinylpentamethyl cyclopentasiloxane.

Accordingly, it would be advantageous for a polymer to have certainproperties of known polymers without the brittleness and high rigiditythat are usually associated therewith. It would be further advantageousfor the polymer to have high acid and fuel resistance such that it wouldbe suitable for use in fields which require polymers having moreflexibility.

One potential use of such polymers is in the automotive industry as anencapsulant for items such as sensors, and especially as an encapsulantfor pressure sensors. Such encapsulants must have an extremely highresistance to acids and fuels. For example, two fuels commonly utilizedfor material evaluation by the automobile industry, Fuel C and FuelCM85, both cause polymer degradation to many known polymers. Fuel C is ahydrocarbon fuel which is approximately 50% by volume isooctane and 50%by volume toluene. Fuel CM85 comprises Fuel C containing 85% by volumemethanol. In addition many materials are tested by the automotiveindustry for their resistance to used synthetic oil, which also causespolymer degradation. For the purpose of this patent, this is defined asMobile 1 Oil, which has been used to lubricate an automotive engine fora minimum of 3,000 miles.

SUMMARY OF THE INVENTION

The present invention discloses a cross-linkable and cross-linkedorganosilicon polymer which is prepared from a mixture of a reactivepolysiloxane resin having both reactive carbon-carbon double bonds andsilicone-hydrogen groups, characterized by alternating structures ofpolycyclic polyene residue and cyclic polysiloxane (or tetrahedralsiloxysilane) residue, hereafter referred to as a silicon hydrocarboncrosslinking agent, and either a vinyl terminated fluorine-containingpolysiloxane or a vinyl terminated phenyl-substituted polysiloxane. Inan alternative embodiment, the polymer comprises a mixture of vinylterminated phenyl-substituted polysiloxane and vinyl terminated fluorinecontaining polysiloxane and the silicon hydrocarbon crosslinking agent.In a further alternative embodiment, vinyl substituted polymethylsiloxanes are used with optionally, phenyl substituted siloxane. Thevinyl substituted polymethyl siloxanes are preferably methyl divinylsiloxane with a molecular weight greater than 100,000.

DETAILED DESCRIPTION OF THE INVENTION

Upon exposure to harsh environments, such as those associated with fuelsand/or acids and/or extreme temperatures, fluorosilicone and phenylsilicone polymers can breakdown and degrade. Consequently, elastomerscomprising either material only provide moderate resistance todegradation upon exposure to fuels and/or acids and/or extremetemperatures. A combination of phenyl-silicone and/or fluorosiliconewith certain forms of cross-linking agents has been found to result in apolymer which maintains its elastomeric properties during and afterexposure to fuels and acids. Specifically, a vinyl terminatedfluorine-containing polysiloxane and/or a vinyl terminatedphenyl-substituted polysiloxane have been shown to be effective whencombined with silicon hydrocarbon crosslinking agents. Exemplary vinylterminated fluorine-containing polysiloxanes include Nusil PLY-7801,Nusil PLY (1-5)-7580, supplied by Nusil Technology, 1050 Cindy Lane,Carpinteria, Calif. 93013 and Gelest FMV-4031, supplied by Gelest, Inc.,Tullytown, Pa. 19007-6308, USA. Exemplary vinyl terminatedphenyl-substituted siloxanes include Nusil PLY (1-5)-7560, NusilPLY-7664, Nusil PLY-7450, supplied by Nusil Technology; Gelest PMV-9925,Gelest PDV-0325, Gelest PDV-0331, Gelest PDV-0341, Gelest PDV-0346,Gelest PDV-0525,Gelest PDV-0541, Gelest PDV-1625, Gelest PDV-1631,Gelest PDV 1635, Gelest PDV-1641, Gelest PDV-2331, Gelest PDV-2335,supplied by Gelest, Inc; Andersil SF 1421; Andersil SF 1712; supplied byAnderson & Associates LLC., Summit, N.J. The reaction of many standardcross-linking agents, such as linear hydrosiloxane chain crosslinkerswith either dimethyl or 3,3,3-trifluoropropyl substitution, with thepolysiloxanes described above results in polymers with little or onlymoderate fuel and acid resistance. It has been determined that combiningvinyl-terminated phenyl-substituted polysiloxane or vinyl terminatedfluorine-containing polysiloxane with a silicon hydrocarbon crosslinkingagent, provides a polymer with superior resistance to the harshconditions imposed by fuels and acids.

Exemplary silicon hydrocarbon crosslinking agents are comprised of acyclic or linear poly(organohydrosiloxane) having at least 30% of itssilicon-hydrogen groups reacted with hydrocarbon residues derived frompolycyclic polyenes. Numerous examples of poly(organohydrosiloxane) areknown. One exemplary poly(organohydrosiloxane) ismethylhydrocyclosiloxane, examples of typical structures include

with typically D4 (n=4) and D5 (n=5). Further exemplarypoly(organohydrosiloxanes) include Tetra- andpenta-methylcyclotetrasiloxane; tetra, penta, hexa andhepta-methylcyclopentasiloxane; tetra-, penta- andhexa-methylcyclohexasiloxane; tetraethyl cyclotetrasiloxanes andtetraphenyl cyclotetrasiloxane; or blends thereof. Exemplary linearsiloxanes include tetrakisdimethylsiloxysilane,tetrakisdiphenylsiloxysilane, and tetrakisdiethylsiloxysilane.

The silicon hydrocarbon crosslinking agents used in this invention areformed by the hydrosilation reaction of the poly(organohydrosiloxane)with a polycyclic polyene. The stoichiometric ratio of carbon-carbondouble bonds to silicon-hydrogen linkages can be in the range of about2:1 to 1:4. A preferred range is about 1:1. Useful cyclic polyenes arepolycyclic hydrocarbon compounds having at least two non-aromatic,non-conjugated carbon-to-carbon double bonds. Exemplary compounds arewell known in the art, and include cyclopentadiene oligomers such asdicyclopentadiene,

and tricyclopentadiene,

Further exemplary compounds include the Diels-Alder oligomers of thedicyclopentadiene and tricyclopentadiene species described above andsubstituted derivatives of the dicyclopentadiene and tricyclopentadienespecies described above including dimethanohexahydronapthalene, methyldicyclopentadiene; and any mixture of these compounds.

An exemplary silicon hydrocarbon crosslinking agent has the followingstructure

Hereafter, this molecule will be referred to as crosslinker SC-1. Afurther exemplary silicon hydrogen crosslinking agent has the followingstructure

In a preferred formulation, the resulting polymer comprises about 64 to99 wt % and most preferably about 77 to 90 wt % of a vinyl terminatedfluorine-containing polysiloxane, which is about 20 to 90 mol % and mostpreferably about 20–60 mol % substituted with 3,3,3-trifluoropropylgroups, and about 1 to 36 wt % and most preferably about 10 to 23 wt %of the silicon hydrocarbon crosslinking agent described above. Theresulting polymers are cross-linked silicone gels with the inherentelastomeric and high temperature properties of gel silicones,accompanied by superior strength and toughness. The resulting polymersadditionally demonstrate excellent fuel resistance and good acidresistance. Materials of this type are useful as coating, potting orencapsulant materials to protect electric/electronic components andassemblies.

In another preferred formulation, the resulting polymer comprises about1 to 40 wt % and most preferably 1–20 wt % of a vinyl terminatedfluorine containing polysiloxane, which is about 20 to 90 mol % and mostpreferably about 20–60 mol % substituted with 3,3,3-trifluoropropylgroups, and about 60 to 99 wt % and most preferably about 80 to 99 wt %of the silicon hydrocarbon crosslinking agent described above. Theresulting polymer is a cross-linked, rigid silicone which demonstratesreduced brittleness and improved toughness compared to the fully crosslinked silicon hydrocarbon material. Furthermore the resulting polymerdemonstrates increased hydrophobicity and lippophobicity indicating thatthis material will also exhibit resistance to fuels, oils and acids.This type of material is useful for the protective encapsulation ofelectric/electronic components where strength, toughness and mechanicalstability are required.

In another preferred formulation, the resulting polymer comprises about20 to 99 wt % and most preferably about 60 to 99 wt % of a vinylterminated phenyl-substituted siloxane, which is about 1 to 40 mol % andmost preferably about 2 to 20 mol % phenyl substituted, and about 1 to80 wt % and most preferably about 1 to 40 wt % of the siliconhydrocarbon crosslinking agent described above. The resulting polymersare a range of cross-linked silicones which vary in hardness from softgels to elastomers and rigid materials. The gel materials demonstratesuperior strength and toughness while retaining the flexibility normallyassociated with this type of material. The rigid materials demonstrate adegree of flexibility and resilience beyond that expected of typicalrigid elastomers. Both categories of material have been shown to beresistant to acid and alcohol based fuels. Materials of this type areuseful as coating, potting or encapsulant materials to protectelectric/electronic components and assemblies.

In another preferred formulation, the resulting polymer comprises about64 to 99 wt % and most preferably about 77 to 90 wt % of a blend of avinyl terminated fluorine-containing polysiloxane and a vinyl terminatedphenyl-substituted polysiloxane and about 1 to 36 wt % and mostpreferably about 10 to 23 wt % of the silicon hydrocarbon crosslinkingagent described above. The blend of vinyl terminated fluorine-containingpolysiloxane and a vinyl terminated phenyl-substituted polysiloxanecomprises about 70 to 99 wt % and most preferably about 80 to 99 wt % ofa vinyl terminated fluorine-containing polysiloxane, which is about 20to 90 mol % and most preferably about 20 to 60 mol % substituted with3,3,3-trifluoropropyl groups, and about 1 to 30 wt % and most preferably1 to 20 wt % of a vinyl terminated phenyl-substituted siloxane, which is1 to 40 mol % and most preferably about 2 to 20 mol % phenylsubstituted. The resulting polymers are flexible cross-linked gels. Thepolymers would be expected to demonstrate similar levels of fuel, oiland acid resistance seen from the fluorosilicone in combination with thesilicon hydrocarbon cross linker and the phenylsilicone in combinationwith the silicon hydrocarbon cross linker. Such polymers would also beexpected to be useful as encapsulants, coatings and sealants for theautomotive, avionics and general electronics markets.

The vinyl terminated fluorine-containing polysiloxane and/or the vinylterminated phenyl-substituted polysiloxane and the silicon hydrocarboncrosslinking agents are combined via an addition-cure reaction. Thevinyl terminated fluorine-containing polysiloxane is blended with agroup VIII metal catalyst and a crosslinking agent. Exemplary group VIIImetal catalysts include platinum based compounds includingchloroplatinic acid, platinum chloride, dibenzonitrile platinumdichloride, platinum on carbon, platinum on silica, platinum on aluminaand olefinic complexes. Further exemplary group VIII metal catalystsinclude rhodium based compounds, including RhCl(PPh₃)₃, RhCl(CO)(PPh₃)₂,ruthenium based compounds, including Ru₃(CO)₁₂, Iridium based compounds,including IrCl(CO)(PPh₃)₄ and paladium based compounds, includingPd(PPh₃)₄. Various additives may be added to the compositions of theinventions in order to enhance their practical usage. Useful additivesinclude materials which are added for the purpose of enhancing thestability and flow properties of the formulation, materials which areadded to control the reactivity of the formulation and further materialswhich are added to enhance the final application, for example adhesion,of the product. Specifically, these additives include fillers, which maybe metallic, mineral or organic materials, compatibilizers, flow controlagents, air release agents, cure rate modifiers, adhesion promoters andanti-oxidants. The formulation ingredients are blended togethermechanically by different mixing methods to achieve uniform blends anddeaerated under vacuum. The resulting blend is placed in a mold suitablefor the preparation of test pieces and cured at a temperature of 100 to150° C. and a time of several minutes to several hours and mostpreferably a temperature of 130 to 150° C. and a time of 1 to 2 hours.

In an alternative embodiment, vinyl functional polydimethyl siloxanesare incorporated either with or without phenyl substituted siloxanes.The phenyl substituted siloxane is vinyl functional and would preferablyhave a high molecular weight, greater than 50,000. The vinyl functionalpolydimethyl siloxane is a high molecular weight methyl divinylsiloxane. The molecular weight of the methyl divinyl siloxane wouldpreferably be greater than 100,000. The additives that are used in theearlier embodiments, such as metal catalysts and adhesion promoters mayalso be incorporated as desired into this embodiment. Further, siliconegum and/or rubber particles may also be incorporated into thisembodiment. When phenyl substituted siloxane is not incorporated intothe polymer, it is preferred that fumed silica be added as a filler. Inthis embodiment the material comprises in the range of about 1 wt % toabout 60 wt %, and preferably in the range of about 5 wt % to about 25wt %, of the vinyl functional polydimethyl siloxanes and about 1 toabout 80 weight percent of the crosslinking agent. This embodiment maybe utilized as an encapsulant or adhesive and is particularlyadvantageous for ink jet printer applications.

While not intending to be limiting in any manner, the present inventionmay be better understood by reference to the following example.

EXAMPLES

The invention can be illustrated by the following examples.

Examples 1 to 3 include gels prepared from a vinyl terminated fluorinecontaining polysiloxane and the silicon hydrocarbon cross linking agent.

Example 1

An encapsulant polymer gel was prepared from a vinyl terminated fluorinecontaining polysiloxane which is 50 mol % substituted with3,3,3-trifluoropropyl groups and the silicon hydrocarbon cross linkingagent described above, via a two-part process. To prepare the firstpart, a mixing vessel equipped with a low shear stirrer was charged with50 wt % of compound A, which is the vinyl terminated polysiloxane, givenin Table 1. With low speed stirring, compound B, which is the group VIIImetal catalyst and other additives, given in Table 1 were added to themixing vessel and blended for a period of 5–30 minutes at roomtemperature. Entrapped air was removed from the resulting blend byevacuating the mixture in a vacuum chamber capable of providing a vacuumof 29 mmHg. To prepare the second part, a further mixing vessel equippedwith a low shear stirrer was charged with the remaining 50 wt % ofcompound A, which is the vinyl terminated polysiloxane, given inTable 1. With low speed stirring, compound C, which is the cross linkingagent, was added to the reaction vessel and blended for a period of 5 to30 minutes at room temperature. Entrapped air was removed from theresulting blend by evacuating the mixture in a vacuum chamber capable ofproviding a vacuum of 29 mmHg. The two parts thus prepared were mixed.The reaction mixture containing compounds A and B was added to thereaction mixture containing compounds A and C and mixed for 5 to 30minutes at room temperature. Entrapped air was removed from theresulting blend by evacuating the mixture in a vacuum chamber capable ofproviding a vacuum of 29 mmHg. The resulting blend was poured into moldssuitable for making test pieces and cured at 150° C. for 1 hour.

TABLE 1 Compound Material Amount A Nusil PLY-7801 (%) 85.8 B Baysilone UCatalyst PT/L (%) 0.3 A-187 (%) 1.0 C SC-1 (%) 12.9

Baysilone U Catalyst PT/L is a group VIII catalyst supplied by GESilicones, 260 Hudson River Road, Waterford, N.Y. 12188. A187 is asilane adhesion promoter supplied by OSi Specialties Inc., PO Box 38002,South Charleston, W.Va., 25303.

Specimens were cut from each cured piece and measured for physicalproperties according to ASTM D2240 and ASTM D 412 (using Die D to cutthe pieces and a tensile rate of 20 inch/minute) and adhesion propertiesaccording to ASTM D-413-82 (type B 90°, peel rate 0.2 inches per minute)with the results shown below.

Hardness (Shore 00) 40 Tensile Strength (psi) 56 Elongation (%) 420Adhesion to PPS (J/m²) 149 Adhesion to Gold (J/m²) 175Note: In general values associated with hardness, tensile strength, %elongation, toughness and adhesion are subject to approximately a 10%experimental error.

Specimens were also examined for heat resistance according to ASTM D 573and chemical resistance according to ASTM D 471, part 15.4.1 (using DieD). The results are shown in Tables 2 to 5.

TABLE 2 Heat at 180° C. Time (hours) Initial 200 400 Hardness (Shore 00)40 62 69 Weight change (%) — −0.5% −1.66

TABLE 3 Fuel C and Fuel CM 85 for 200 hours at 25° C. Fuel C Fuel CM 85Tensile strength retention (%) 164 126 Elongation retention (%) 146 125Adhesion to PPS retention (%) 159 146 Adhesion to gold retention (%) 150120

TABLE 4 Mobil 1 Oil at 140° C. Time (hours) 200 400 600 Tensile strengthretention (%) 112 90 110 Elongation retention (%) 121 102 102 Adhesionto PPS retention (%) 85 82 83 Weight gain (%) +2.3 +2.7 —

TABLE 5 Nitric and sulfuric acid at pH 1.6 and 85° C. Nitric acidSulfuric acid Time (hours) 620 1000 620 1000 Tensile strength retention(%) 104 121 122 100 Elongation retention (%) 83 95 92 80 Adhesion to PPSretention (%) 100 84 106 106 Adhesion to gold retention (%) 88 80 73 87

The performance properties detailed above describing Example 1illustrate that this vinyl terminated fluorine containing polysiloxanein combination with the silicon hydrocarbon crosslinker is a soft gelmaterial with excellent strength, flexibility and adhesion properties.Moreover, excellent retention of these properties is observed onexposure of this material to fuels, oils and acids.

Example 2

Example 2 represents four formulations which demonstrate that similarproperties to the material described in Example 1 can be achieved for arange of levels of the silicon hydrocarbon crosslinker. Encapsulantpolymer gels were prepared from varying ratios of a vinyl terminatedfluorine containing polysiloxane which is 50 mol % substituted with3,3,3-trifluoropropyl groups and the silicon hydrocarbon cross linkingagent described above. Materials in Example 2 were formulated accordingto the method described in Example 1, via a two part process. Compound Bshown in Table 6 was blended with 50 wt % of compound A. Compound Cshown in Table 6 was blended with the remaining 50 wt % of compound A.The two parts were mixed, de-aerated, poured into molds suitable formaking test pieces and cured at 150° C. for 1 hour.

TABLE 6 Ex Compound Material Ex 2.1 Ex 2.2 Ex 2.3 2.4 A Nusil PLY-7801(%) 93.70 86.67 81.70 75.70 B PT-L (%) 0.30 0.30 0.30 0.30 C SC-1 (%)6.00 13.03 18.00 24.00

Specimens were cut from each cured piece and measured for physicalproperties according to ASTM D2240 and ASTM D 412 (using Die D to cutthe pieces and a tensile rate of 20inch/minute) with the results shownbelow.

Ex 2.1 Ex 2.2 Ex 2.3 Ex 2.4 Hardness (Shore 00) 56 59 63 65 Tensilestrength (psi) 45.39 77.79 106.4 70.68 Elongation (%) 210.7 218.8 194.9139.5 Toughness (in.lbs/in³) 41.07 66.09 85.43 47.44

Specimens were also examined for heat resistance according to ASTM D 573and chemical resistance according to ASTM D 471, part 15.4.2, (using DieD). The results are shown in Tables 7 to 10.

TABLE 7 Heat for 200 hours at 180° C. Ex 2.1 Ex 2.2 Ex 2.3 Ex 2.4Hardness (Shore 00) 69 69.5 72 74 Tensile strength retention (%) 152 137110 106 Elongation retention (%) 58 58 54 44 Toughness retention (%) 9477 63 42

TABLE 8 Fuel C for 200 hours at 25° C. Ex 2.1 Ex 2.2 Ex 2.3 Ex 2.4Hardness (Shore 00) 57 59 63.5 65 Tensile strength retention (%) 134 120122 114 Elongation retention (%) 107 105 104 106 Toughness retention (%)178 145 133 118

TABLE 9 Fuel CM 85 for 200 hours at 25° C. Ex 2.1 Ex 2.2 Ex 2.3 Ex 2.4Hardness (Shore 00) 56.5 59 63 65 Tensile strength retention (%) 117 94118 120 Elongation retention (%) 107 96 106 108 Toughness retention (%)139 100 125 123

TABLE 10 Nitric acid for 120 hours at pH 1.0, 85° C. Ex 2.1 Ex 2.2 Ex2.3 Ex 2.4 Hardness (Shore 00) — 60 65 64 Tensile strength retention (%)— 105 111 88 Elongation retention (%) — 97 99 89 Toughness retention (%)— 99 104 80

Example 3

Example 3 represents a further formulation which demonstrates thatsimilar properties to the material described in Example 1 can beachieved for vinyl terminated fluorine containing polysiloxanes withalternative levels of 3,3,3-trifluoropropyl substitution. An encapsulantpolymer gel was prepared from a vinyl terminated fluorine containingpolysiloxane which is 40 mol % substituted with 3,3,3-trifluoropropylgroups and the silicon hydrocarbon cross linking agent described above.The material in Example 3 was formulated according to the methoddescribed in Example 1, via a two part process. Compound B shown inTable 11 was blended with 50 wt % of compound A. Compound C shown inTable 11 was blended with the remaining 50 wt % of compound A. The twoparts were mixed, de-aerated, poured into molds suitable for making testpieces and cured at 150° C. for 1 hour.

TABLE 11 Compound Material A FMV-4031 (%) 81.70 B PT-L (%) 0.30 C SC-1(%) 18.00Specimens were cut from each cured piece and measured for physicalproperties according to ASTM D2240 and ASTM D 412 (using Die D to cutthe pieces and a tensile rate of 20 inch/minute) with the results shownbelow.

Hardness (Shore 00) 60 Tensile strength (psi) 89 Elongation (%) 268Toughness (in.lbs/in³) 104Specimens were also examined for heat resistance according to ASTM D 573and chemical resistance according to ASTM D 471, part 15.4.2, (using DieD). The results are shown in Table 12.

TABLE 12 Heat and chemical resistance Conditions Nitric acid Heat Fuel CFuel CM 85 pH 1.0, 180° C. 25° C. 25° C. 85° C. Time (hours) 200 200 200120 Hardness (Shore 00) 67 62 61 63 Tensile strength 139 91 93 119retention (%) Elongation retention (%) 53 93 97 97 Toughness retention(%) 67 94 94 107

Comparative Example 1

A further encapsulant polymer gel was prepared from a vinyl terminatedfluorine containing polysiloxane which is 50 mol % substituted with3,3,3-trifluoropropyl groups and a cross linking agent that is a linearhydrosiloxane with dimethyl substitution, Masil XL-1, supplied by PPGIndustries Inc., Specialty Chemicals, 3938 Porett Drive, Gurnee, Ill.60031. A further encapsulant polymer gel was prepared from a vinylterminated fluorine containing polysiloxane which is 50 mol %substituted with 3,3,3-trifluoropropyl groups and a cross linking agentthat is a linear hydrosiloxane with 3,3,3-trifluoropropyl substitution,SMP 9951-22, supplied by Nusil Technology, 1050 Cindy Lane, Carpinteria,Calif. 93013. Materials in Comparative Example 1 were formulatedaccording to the method described in Example 1, via a two part process.Compound B shown in Table 13 was blended with 50 wt % of compound A.Compound C shown in Table 13 was blended with the remaining 50 wt % ofcompound A. The two parts were mixed, de-aerated, poured into moldssuitable for making test pieces and cured at 150° C. for 1 hour

TABLE 13 Compound Material CEx 1.1 CEx 1.2 A Nusil PLY-7801 (%) 81.7081.70 B PT-L (%) 0.30 0.30 C Masil XL-1 (%) 18.00 — SMP 9951-22 (%) —18.00Specimens were cut from each cured piece and measured for physicalproperties according to ASTM D2240 and ASTM D 412 (using Die D to cutthe pieces and a tensile rate of 20inch/minute) with the results shownbelow.

CEx 1.1 CEx 1.2 Hardness (Shore 00) 59 46 Tensile strength (psi) 38 35Elongation (%) 117 236 Toughness (in.lbs/in³) 39 49Specimens were also examined for heat resistance according to ASTM D 573and chemical resistance according to ASTM D 471, part 15.4.2, (using DieD). The results are shown in Tables 14 to 17.

TABLE 14 Heat for 200 hours at 180° C. CEx 1.1 CEx 1.2 Hardness (Shore00) 73 54 Tensile strength retention (%) 108 45 Elongation retention (%)37 50 Toughness retention (%) 14 6

TABLE 15 Fuel C for 200 hours at 25° C. CEx 1.1 CEx 1.2 Hardness (Shore00) 62.5 53 Tensile strength retention (%) 83 64 Elongation retention(%) 87 71 Toughness retention (%) 40 36

TABLE 16 Fuel CM 85 for 200 hours at 25° C. CEx 1.1 CEx 1.2 Hardness(Shore 00) 61 45 Tensile strength retention (%) 94 75 Elongationretention (%) 69 86 Toughness retention (%) 44 56

TABLE 17 Nitric acid for 120 hours at pH 1.0, 85° C. CEx 1.1 CEx 1.2Hardness (Shore 00) 53 42 Tensile strength retention (%) 28 67Elongation retention (%) 110 94 Toughness retention (%) 8 44

The performance properties detailed above describing Comparative Example1 illustrate that this vinyl terminated fluorine containing polysiloxanein combination with cross linking agents that are linear hydrosiloxaneswith either dimethyl or 3,3,3-trifluoropropyl substitution are soft gelmaterials with inferior strength and toughness compared with Examples 1to 3. Moreover these properties are observed to deteriorate on exposureof this material to both fuels and acids, indicating polymerdegradation.

Example 4

Example 4 describes a range of rigid polymers prepared from a vinylterminated fluorine containing polysiloxane and the silicon hydrocarboncross linking agent. These were prepared from varying ratios of a vinylterminated fluorine containing polysiloxane which is 50 mol %substituted with 3,3,3-trifluoropropyl groups and the siliconhydrocarbon cross linking agent described above. Materials in Example 4were formulated according to the method described in Example 1, via atwo part process. Compound B shown in Table 18 was blended with 50 wt %of compound A. Compound C shown in Table 18 was blended with theremaining 50 wt % of compound A. The two parts were mixed andde-aerated.

TABLE 18 Ex Compound Material Ex 4.1 Ex 4.2 Ex 4.3 4.4 A Nusil PLY-7801(%) — 4.99 9.97 19.94 B PT-L (%) 0.30 0.30 0.30 0.30 C SC-1 (%) 99.7094.72 89.73 79.76

Films coated on glass slides were prepared by drawing down materialusing 2 mil tape to define the film thickness. These films were cured at150° C. for 1 hour. Contact angle data for water and toluene on thefilms were measured by the sessile drop method: a drop of the test fluidwas placed onto the film surface in air and the contact angle wasmeasured after ten seconds at 25° C., with the results shown below.

Ex 4.1 Ex 4.2 Ex 4.3 Ex 4.4 Hardness (Shore D) 71 68.3 64.3 62.3 Contactangle: Water 78° 78° 85° 86° Toluene  0° 23° 25° 30°

The performance properties detailed above describing Example 4illustrate that the incorporation of this vinyl terminated fluorinecontaining polysiloxane with the silicon hydrocarbon crosslinker resultsin a rigid polymer with reduced hardness compared with the fullycrosslinked silicon hydrocarbon material, thus the polymer would beexpected to have reduced brittleness and improved toughness comparedwith the fully crosslinked silicon hydrocarbon material. Moreover,Example 4 demonstrates that this improved toughness is accompanied by anincrease in contact angle for both water and toluene, indicating thatthe polymer has increased hydrophobicity and lippophobicity, thus thepolymer would be expected to have improved resistance to fuels, oils andacids.

Examples 5 to 7 include elastomers prepared from a vinyl terminatedphenyl substituted polysiloxanes and the silicon hydrocarbon crosslinking agent.

Example 5

An encapsulant polymer elastomer was prepared from a vinyl terminatedphenyl-substituted polysiloxane which is 6 mol % substituted phenylgroups and the silicon hydrocarbon cross linking agent described above.The material in Example 5 was formulated according to the methoddescribed in Example 1, via a two part process. Compound B shown inTable 19 was blended with 50 wt % of compound A. Compound C shown inTable 19 was blended with the remaining 50 wt % of compound A. The twoparts were mixed, de-aerated, poured into molds suitable for making testpieces and cured at 150° C. for 1 hour.

TABLE 19 Compound Material A Andersil SF 1721 (%) 86.9 B PT-L (%) 0.1 CSC-1 (%) 13.0Specimens were cut from each cured piece and measured for physicalproperties according to ASTM D2240 and ASTM D 412 (using Die D to cutthe pieces and a tensile rate of 20inch/minute) and adhesion propertiesaccording to ASTM D-413-82 (type B 90°, peel rate 0.2 inches per minute)with the results shown below.

Hardness (Shore A) 14 Tensile Strength (psi) 130 Elongation (%) 285Adhesion to PPS (J/m²) 121 Adhesion to Gold (J/m²) 86Specimens were also examined for heat resistance according to ASTM D 573and chemical resistance according to ASTM D 471, part 15.4.1 (using DieD). The results are shown in Tables 20 to 22.

TABLE 20 Heat at 180° C. Time (hours) initial 200 Hardness (Shore A) 1428 Weight change (%) — −1.76

TABLE 21 Fuel CM 85 for 150–200 hours at 25° C. Fuel CM 85 Tensilestrength retention (%) 78 Elongation retention (%) 94 Adhesion to goldretention (%) 124

TABLE 22 Sulfuric Acid at pH 1.6, at 85° C. Sulfuric acid Time (hours)620 1000 Tensile strength retention (%) 69 95 Elongation retention (%)77 166 Adhesion to gold retention (%) 122 122

The performance properties detailed above describing Example 5illustrate that this vinyl terminated phenyl substituted polysiloxane incombination with the silicon hydrocarbon crosslinker is an elastomerwith excellent strength and adhesion properties. Moreover, excellentretention of these properties is observed on exposure of this materialto alcohol based fuels and acids.

Example 6

Example 6 represents a further formulation which demonstrates thatsimilar properties to the material described in Example 5 can beachieved for an increased level of the silicon hydrocarbon crosslinker.An encapsulant polymer elastomer was prepared from a vinyl terminatedphenyl-substituted polysiloxane which is 6 mol % substituted with phenylgroups and the silicon hydrocarbon cross linking agent described above.The material in Example 6 was formulated according to the methoddescribed in Example 1, via a two part process. Compound B shown inTable 23 was blended with 50 wt % of compound A. Compound C shown inTable 23 was blended with the remaining 50 wt % of compound A. The twoparts were mixed, de-aerated, poured into molds suitable for making testpieces and cured at 150° C. for 1 hour.

TABLE 23 Compound Material A Andsil SF 1721(%) 81.70 B PT-L (%) 0.30 CSC-1 (%) 18.00Specimens were cut from each cured piece and measured for physicalproperties according to ASTM D2240 and ASTM D 412 (using Die D to cutthe pieces and a tensile rate of 20inch/minute) with the results shownbelow.

Hardness (Shore 00) 69 Tensile strength (psi) 126 Elongation (%) 172Specimens were also examined for heat resistance according to ASTM D 573and chemical resistance according to ASTM D 471, part 15.4.2 (using DieD). The results are shown in Table 24.

TABLE 24 Conditions Heat Fuel C Fuel CM 85 Nitric acid 180° C. 25° C.25° C. pH 1.0, 85° C. Time (hours) 200 200 200 120 Hardness (Shore 00)81 70 68 70 Tensile strength 211 122 101 132 retention (%) Elongationretention 46 106 90 87 (%)

The performance properties detailed above describing Example 6illustrate that this vinyl terminated phenyl substituted polysiloxane incombination with an increased level of the silicon hydrocarboncrosslinker is an elastomer with excellent strength and adhesionproperties. Moreover, excellent retention of these properties isobserved on exposure of this material to fuels and acids.

Example 7

Example 7 represents six formulations which demonstrate that similarbenefits observed for the materials described in Examples 5 and 6 can beachieved with vinyl terminated phenyl substituted polysiloxanes withalternative levels of phenyl substitution and for a range of levels ofthe silicon hydrocarbon crosslinker. Encapsulant polymer elastomers wereprepared from varying ratios of a vinyl terminated phenyl-substitutedpolysiloxane which is 15 mol % substituted phenyl groups and the siliconhydrocarbon cross linking agent described above. Materials in Example 7were formulated according to the method described in Example 1, via atwo part process. Compound B shown in Table 25 was blended with 50 wt %of compound A. Compound C shown in Table 25 was blended with theremaining 50 wt % of compound A. The two parts were mixed, de-aerated,poured into molds suitable for making test pieces and cured at 150° C.for 1 hour.

TABLE 25 Ex Ex Ex Ex Ex Ex Compound Material 7.1 7.2 7.3 7.3 7.4 7.5 ANusil PLY- 93.70 86.67 81.70 75.70 69.70 59.70 7664 (%) B PT-L (%) 0.300.30 0.30 0.30 0.30 0.30 C SC-1 (%) 6.00 13.03 18.00 24.00 30.00 40.00Specimens were cut from each cured piece and measured for physicalproperties according to ASTM D2240 and ASTM D 412 (using Die D to cutthe pieces and a tensile rate of 20 inch/minute with the results shownbelow.

Ex Ex Ex Ex Ex 7.1 Ex 7.2 7.3 7.3 7.4 7.5 Hardness (Shore 00) 62.6 70.474.6 83.2 — — Hardness (Shore A) — — — — 53 67 Tensile strength (psi) 40142 197 482 523 672 Elongation (%) 180 173 131 131 95 64 Toughness (in ·lbs/in³) 37 95 99 236 228 227Specimens were also examined for heat resistance according to ASTM D 573and chemical resistance according to ASTM D 471, part 15.4.2 (using DieD). The results are shown in Tables 26 to 29.

TABLE 26 Heat for 200 hours at 180° C. Ex Ex Ex Ex Ex 7.1 Ex 7.2 7.3 7.37.4 7.5 Hardness (Shore 00) 72 82 86 90 — — Hardness (Shore A) — — — —77 87 Tensile strength retention (%) 216 168 147 98 98 126 Elongationretention (%) 45 38 36 29 27 28

TABLE 27 Fuel C for 200 hours at 25° C. Ex Ex Ex Ex Ex 7.1 Ex 7.2 7.37.3 7.4 7.5 Hardness (Shore 00) 60 71 71 82.5 — — Hardness (Shore A) — —— — 77 87 Tensile strength retention (%) 79 87 118 107 — — Elongationretention (%) 94 97 109 102 — —

TABLE 28 Fuel CM 85 for 200 hours at 25° C. Ex Ex Ex Ex Ex Ex 7.1 7.27.3 7.3 7.4 7.5 Hardness (Shore 00) 61 71 75 85 — — Hardness (Shore A) —— — — 54 69 Tensile strength retention (%) 127 94 125 106 103 122Elongation retention (%) 94 90 105 97 101 120

TABLE 29 Nitric acid for 120 hours at pH 1.0, 85° C. Ex Ex Ex Ex Ex 7.1Ex 7.2 7.3 7.3 7.4 7.5 Hardness (Shore 00) 62 73 77 85 — — Hardness(Shore A) — — — — 59 77 Tensile strength 189 125 120 105 117 124retention (%) Elongation retention (%) 110 88 89 83 86 84

The performance properties detailed above describing Example 7illustrate that this vinyl terminated phenyl substituted polysiloxane incombination with the silicon hydrocarbon crosslinker can be a soft gelmaterial with excellent strength and toughness. Moreover, good retentionof these properties is observed on exposing these materials to fuels andacids. The heat resistance of this material is equal to or better than avinyl terminated phenyl substituted polysiloxane in combination with across linking agent that is a linear hydrosiloxane with dimethylsubstitution (see Comparative Example 2). Furthermore, at increasedlevels of the silicon hydrocarbon crosslinker, more rigid materials aregenerated which demonstrate greatly increased levels of toughness whileremaining flexible. Moreover, good retention of these properties isobserved on exposing these materials to acids and alcohol based fuels.

Comparative Example 2

A further encapsulant polymer gel was prepared from a vinyl terminatedphenyl-substituted polysiloxane which is 15 mol % substituted phenylgroups and a cross linking agent that is a linear hydrosiloxane withdimethyl substitution. The material in Comparative Example 2 wasformulated according to the method described in Example 1, via a twopart process. Compound B shown in Table 30 was blended with 50 wt % ofcompound A. Compound C shown in Table 30 was blended with the remaining50 wt % of compound A. The two parts were mixed, de-aerated, poured intomolds suitable for making test pieces and cured at 150° C. for 1 hour.

TABLE 30 Compound Material A Nusil PLY-7664 (%) 81.70 B PT-L (%) 0.30 CMasil XL-1 (%) 18.00Specimens were cut from each cured piece and measured for physicalproperties according to ASTM D2240 and ASTM D 412 (using Die D to cutthe pieces and a tensile rate of 20 inch/minute) with the results shownbelow.

Hardness (Shore 00) 61.8 Tensile strength (psi) 61.42 Elongation (%)251.2 Toughness (in · lbs/in³) 63.21Specimens were also examined for heat resistance according to ASTM D 573and chemical resistance according to ASTM D 471, part 15.4.2 (using DieD). The results are shown in Table 31.

TABLE 31 Heat and Chemical resistance Conditions Nitric acid Heat Fuel CFuel CM 85 pH 1.0, 180° C. 25° C. 25° C. 85° C. Time (hours) 200 200 200120 Hardness (Shore 00) 78 69 63 71 Tensile strength 299 117 105 206retention (%) Elongation retention (%) 32 74 81 66

The performance properties detailed above describing Comparative Example2 illustrate that this vinyl terminated phenyl substituted polysiloxanein combination with a cross linking agent that is a linear hydrosiloxanewith dimethyl substitution is a soft gel material with inferior strengthand toughness compared with Examples 5 to 7. Moreover these propertiesare observed to deteriorate on exposure of this material to both fuelsand acids, indicating polymer degradation.

Example 8

Example 8 represents two formulations in which a blend of a vinylterminated fluorine containing polysiloxane and a vinyl terminatedphenyl substituted polysiloxane is used in conjunction with the siliconhydrocarbon crosslinker. Encapsulant polymer gels were prepared fromblends of a vinyl terminated fluorine containing polysiloxane, which is50 mol % substituted with 3,3,3-trifluoropropyl groups, and a vinylterminated phenyl-substituted polysiloxane, which is 15 mol %substituted phenyl groups, in different ratios, and the siliconhydrocarbon cross linking agent described above. Materials in Example 8were formulated according to the method described in Example 1, via atwo part process. Compound B shown in Table 32 was blended with 50 wt %each of compounds A. Compound C shown in Table 32 was blended with theremaining 50 wt % each of compounds A. The two parts were mixed,de-aerated, poured into molds suitable for making test pieces and curedat 150° C. for 1 hour.

TABLE 32 Compound Material Ex 8.1 Ex 8.2 A Nusil PLY-7801 (%) 65.3673.53 Nusil PLY-7664 (%) 16.34 8.17 B PT-L (%) 0.30 0.30 C SC-1 (%)18.00 18.00Specimens were cut from each cured piece and measured for physicalproperties according to ASTM D2240 and ASTM D 412 (using Die D to cutthe pieces and a tensile rate of 20 inch/minute) with the results shownbelow.

Ex 8.1 Ex 8.2 Hardness (Shore 00) 71 64 Tensile strength (psi) 69 64Elongation (%) 111 185 Toughness (in.lbs/in³) 46 49Specimens were also examined for heat resistance according to ASTM D573, 180° C. for 200 hours, with the results shown below.

Ex 8.1 Ex 8.2 Hardness (Shore 00) 81 75 Tensile strength retention (%)120 132 Elongation retention (%) 45 41 Toughness retention (%) 81 49

The performance properties detailed above describing Example 8illustrate that blends of vinyl terminated fluorine containingpolysiloxane and vinyl terminated phenyl substituted polysiloxane incombination with the silicon hydrocarbon crosslinker are gel materialswith good strength, flexibility and heat resistance.

Comparative Example 3

A further encapsulant polymer gel was prepared from a blend of a vinylterminated fluorine containing polysiloxane which is 50 mol %substituted with 3,3,3-trifluoropropyl groups with a vinyl terminatedphenyl-substituted polysiloxane which is 15 mol % substituted withphenyl groups and a cross linking agent that is a linear hydrosiloxanewith either dimethyl substitution or 3,3,3-trifluoropropyl substitution.Materials in Comparative Example 3 were formulated according to themethod described in Example 1, via a two part process. Compounds B shownin Table 33 was blended with 50 wt % each of compounds A. Compound Cshown in Table 33 was blended with the remaining 50 wt % each ofcompounds A. The two parts were mixed, de-aerated, poured into moldssuitable for making test pieces and cured at 150° C. for 1 hour.

TABLE 33 Compound Material CEx 3.1 CEx 3.2 A Nusil PLY-7801 (%) 65.3665.36 Nusil PLY-7664 (%) 16.34 16.34 B PT-L (%) 0.30 0.30 C Masil XL-1(%) 18.00 — SMP 9951-22 (%) — 18.00Specimens were cut from each cured piece and measured for physicalproperties according to ASTM D2240 and ASTM D 412 (using Die D to cutthe pieces and a tensile rate of 20 inch/minute with the results shownbelow.

CEx 3.1 CEx 3.2 Hardness (Shore 00) 51.5 33 Tensile strength (psi) 26.416.2 Elongation (%) 134.4 342.4 Toughness (in.lbs/in³) 14 27Specimens were also examined for heat resistance according to ASTM D573, 180° C. for 200 hours, with the results shown below.

CEx 3.1 CEx 3.2 Hardness (Shore 00) 84 54.5 Tensile strength retention(%) 256 121 Elongation retention (%) 14 41 Toughness retention (%) 25 17The performance properties detailed above describing Comparative Example3 illustrate that blends of vinyl terminated fluorine containingpolysiloxane and vinyl terminated phenyl substituted polysiloxane incombination with cross linking agents that are linear hydrosiloxaneswith either dimethyl or 3,3,3-trifluoropropyl substitution are soft gelmaterials with inferior strength, toughness and heat resistance comparedwith Example 8.

Example 9

Six formulations were prepared with various amounts of phenyl containingvinyl silicone and high molecular weight divinyl silicone. The siliconehydrocarbon crosslinking agent, compound C, of the prior examples wasalso incorporated in varying amounts. The ingredients of theformulations are illustrated in Table 34.

TABLE 34 Material 1 2 3 4 5 6 Phenyl 67.2 — — 16.5 4.0 54.9 containingvinyl silicone Methyl — 22.7 12.0 5.5 12.0 — divinyl Crosslink 29.0 64.470.0 64.0 70.0 40.9 Agent Pt Catalyst 0.3 0.3 0.3 0.2 0.2 0.3 Adhesion3.2 3.4 3.4 3.4 3.4 3.8 Promoter Thixotrope — 10.0 9.9 9.5 9.5 —Silicone — — 5.0 2.0 2.0 — RubberFormulation 3 was tested for modulus and the results from the storagemodulus curve are shown in Table 35.

TABLE 35 1 Week 2 Weeks 2 Weeks 2 Weeks Ambient 1 Week 40° C. 40° C. 40°C. Dry 40° C. Dry Magenta Black Yellow Temp (mPa) (mPa) (mPa) (mPa)(mPa) 25° C. 943 1039 1035 1130 1029 40° C. — 992 985 1075 979 70° C.788 882 885 953 853Formulations 1–6 were tested for weight change percentage afterimmersion in commercial aqueous inks for one and two weeks at 40° C. Theresults are illustrated in Table 36.

TABLE 36 1 Week 1 Week 1 Week 2 Weeks 2 Weeks 2 Weeks Sam- 40° C. 40° C.40° C. 40° C. 40° C. 40° C. ple Magenta Black Yellow Magenta BlackYellow 1 0.3 0.1 1.2 0.3 0.1 1.1 2 0.3 0.3 0.7 0.2 0.2 0.7 3 0.1 0.3 0.70.1 0.3 0.8 4 0.5 0.4 1.6 0.3 0.4 1.4 5 0.2 0.4 1.3 0.1 0.4 1.3 6 0.50.1 1.2 0.6 0.1 1.1The results shown in Tables 35 and 36 illustrate that a high levelsilicon hydrocarbon crosslinking agent with a high molecular weightvinyl terminated dimethyl substituted polysiloxane provide a tough, highmodulus product that has low weight change when exposed to aqueous inkjet ink solutions.

Many modifications and variations of this invention can be made withoutdeparting from its spirit and scope, as will be apparent to thoseskilled in the art. The specific embodiments described herein areoffered by way of example only, and the invention is to be limited onlyby the terms of the appended claims, along with the full scope ofequivalents to which such claims are entitled.

1. A crosslinkable organosilicon polymer composition comprisingvinyl-terminated polydimethylsiloxane and between 1 and 80 wt. % of asilicon hydrocarbon crosslinking agent, wherein the crosslinking agentcomprises alternating structures of polycyclic polyene residues andcyclic or tetrahedral siloxysilane residues.
 2. A composition accordingto claim 1, wherein the vinyl functional polydimethyl siloxane isdimethylsiloxane having a vinyl group at each terminus.
 3. A compositionaccording to claim 1, further comprising fumed silica.
 4. A compositionaccording to claim 1, further comprising phenyl substituted siloxanethat is vinyl functional.
 5. A composition according to claim 1comprising in the range of about 1 wt % to about 60 wt % of the vinylfunctional polydimethyl siloxane.
 6. A composition according to claim 5,comprising in the range of about 5 wt % to about 25 wt % of the vinylfunctional polydimethyl siloxane.
 7. A composition according to claim 1,comprising in the range of about 1 wt % to about 40 wt % of the siliconhydrocarbon cross-linking agent.
 8. A composition according to claim 1,further comprising a group VIII metal catalyst.
 9. A compositionaccording to claim 8, wherein the group VIII metal catalyst is selectedfrom the group consisting of platinum based compounds, rhodium basedcompounds, ruthenium based compounds, iridium based compounds, palladiumbased compounds and mixtures thereof.
 10. A composition according toclaim 9, wherein the group VIII metal catalyst is selected from thegroup consisting of chloroplatinic acid, platinum chloride,dibenzonitrile platinum dichloride, platinum on carbon, platinum onsilica, platinum on alumina, olefinic complexes, RhCl(PPh₃)₃,RhCl(CO)(PPh₃)₂, Ru₃(CO)₁₂, IrCl(CO)(PPh₃)₄, Pd(PPh₃)₄, and mixturesthereof.
 11. A composition according to claim 1, wherein the polymerfurther comprises an additive selected from the group consisting ofantioxidants, compatabilizing agents, metallic, mineral and organicfillers, flow control agents, air release agents, adhesion promoters,cure rate modifiers, silicone gum, rubber particles and mixturesthereof.
 12. An electronic sensor module containing the composition ofclaim 1 as a protective encapsulant.
 13. An electronic sensor modulecontaining the composition of claim 1 as an adhesive.